1. Field of the Invention
The present invention relates to a polypropylene resin composition and to a formed article comprising the same. In particular, the invention relates to a polypropylene resin composition superior in rigidity and impact resistance and also particularly superior in drop weight impact strength, and to a formed article made of the same.
2. Description of the Related Art
A polypropylene resin composition including a polypropylene resin and a nucleating agent contained therein is a material with superior mechanical properties. It therefore is used for a wide variety of applications as a material for forming molded articles such as automotive interior or exterior components, home electric materials, containers and sundries.
For example, JP 2-49047 A discloses a propylene polymer composition including a propylene homopolymer with a specific intrinsic viscosity satisfying a specific relationship together with the isotactic pentad fraction of the propylene homopolymer, and an organic phosphorus compound with a specific structure as a nucleating agent, wherein the number of particles of the organic phosphorus compound with a specific size which are contained in a unit weight of the composition is within a specific range.
JP 5-194685 A discloses an ethylene-propylene block copolymer including a crystalline polypropylene portion and an ethylene-propylene random copolymer portion wherein the crystalline polypropylene portion has an intrinsic viscosity, Q factor and content of 20° C. xylene-soluble component each within a specific range, the ethylene-propylene random copolymer portion has an intrinsic viscosity within a specific range and the block copolymer has a content of the copolymer portion within a specific range. The reference also discloses that a nucleating agent may be added for a desired purpose.
Even for the polypropylene resin compositions disclosed in the above-cited references, there is a demand for further improvement in rigidity and impact resistance, and particularly, improvement in drop weight impact strength.